# Nginx configuration for production environment
# HTTP to HTTPS redirect, SSL/TLS, WebSocket support

user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;

events {
    worker_connections 2048;
    use epoll;
}

http {
    include /etc/nginx/mime.types;
    default_type application/octet-stream;

    log_format main '$remote_addr - $remote_user [$time_local] "$request" '
                    '$status $body_size_sent "$http_referer" '
                    '"$http_user_agent" "$http_x_forwarded_for"';

    access_log /var/log/nginx/access.log main;

    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    types_hash_max_size 2048;
    client_max_body_size 50M;

    # Hide nginx version
    server_tokens off;

    # Gzip compression
    gzip on;
    gzip_vary on;
    gzip_proxied any;
    gzip_comp_level 6;
    gzip_types text/plain text/css text/xml text/javascript application/json application/javascript application/xml+rss;

    # Rate limiting (optional, adjust as needed)
    limit_req_zone $binary_remote_addr zone=api_limit:10m rate=100r/m;
    limit_req_zone $binary_remote_addr zone=ws_limit:10m rate=10r/s;

    # Upstream API server
    upstream api {
        server api:3000;
        keepalive 32;
    }

    # HTTP server - redirect to HTTPS
    server {
        listen 80;
        server_name _;

        # Allow Let's Encrypt challenges
        location /.well-known/acme-challenge/ {
            root /var/www/certbot;
        }

        # Redirect all other traffic to HTTPS
        location / {
            return 301 https://$host$request_uri;
        }
    }

    # HTTPS server
    server {
        listen 443 ssl http2;
        server_name _;

        # SSL Configuration
        # Update these paths to match your SSL certificate locations
        ssl_certificate /etc/nginx/ssl/certs/fullchain.pem;
        ssl_certificate_key /etc/nginx/ssl/private/privkey.pem;

        # SSL Security Settings
        ssl_protocols TLSv1.2 TLSv1.3;
        ssl_ciphers 'ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384';
        ssl_prefer_server_ciphers off;
        ssl_session_cache shared:SSL:10m;
        ssl_session_timeout 10m;
        ssl_session_tickets off;

        # Security Headers
        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;
        add_header X-Frame-Options "DENY" always;
        add_header X-Content-Type-Options "nosniff" always;
        add_header X-XSS-Protection "1; mode=block" always;
        add_header Referrer-Policy "strict-origin-when-cross-origin" always;

        # Health check endpoint (no rate limiting)
        location /health {
            proxy_pass http://api/health;
            proxy_http_version 1.1;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            
            access_log off;
        }

        # WebSocket support for Socket.io (with rate limiting)
        location /socket.io/ {
            limit_req zone=ws_limit burst=20 nodelay;
            
            proxy_pass http://api;
            proxy_http_version 1.1;
            
            # WebSocket upgrade headers
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
            
            # Standard proxy headers
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            
            # WebSocket timeouts (Socket.io uses long-lived connections)
            proxy_read_timeout 86400s;
            proxy_send_timeout 86400s;
            proxy_connect_timeout 60s;
            
            # Disable buffering for real-time data
            proxy_buffering off;
            proxy_cache off;
        }

        # API endpoints (with rate limiting)
        location /api/ {
            limit_req zone=api_limit burst=50 nodelay;
            
            proxy_pass http://api;
            proxy_http_version 1.1;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            
            # Timeout settings
            proxy_connect_timeout 60s;
            proxy_send_timeout 60s;
            proxy_read_timeout 60s;
            
            # Buffer settings
            proxy_buffering on;
            proxy_buffer_size 4k;
            proxy_buffers 8 4k;
        }

        # Root endpoint
        location / {
            proxy_pass http://api;
            proxy_http_version 1.1;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
        }
    }
}